Declaration (Sengen 宣言) is the fourth episode of the Accel World Anime. It aired April 27th 2012 in Japan.
As Haruyuki chooses not to meddle with the backdoor program to avoid detection, he leaves Chiyuri's apartment. He later has a dream consisting of both Chiyuri and Kuroyukihime who come on to him in the dream. As he is walking to school, he meets up with Kuroyukihime who apologises for asking him to Cable Link with Chiyuri, to which he says he did it, to which Kuroyukihime stops startled and hurriedly walks to school. When Haruyuki is interviewed by two girls from the Schools Newspaper, and after questioning him, they come to the conclusion that Kuroyukihime legitimately likes him, and that she was jealous, hence the way she acted earlier, which he refuses to believe.
As Kuroyukihime and Haruyuki walk together and discussed about Haruyuki's investigation on Cyan Pile's true identity, Haruyuki resigns himself to just being a pawn, which then causes him to receive a slap from Kuroyukihime and being called an idiot by her as well. As she is reprimanding him, an out of control car heads straight towards Haruyuki and Kuroyukihime, prompting them to go into the Accelerated World. While they are in the Accelerated World, Haruyuki finds that Araya intended to create an accident to revenge against Haruyuki as the current technology should have prevented accidents from happening. Kuroyukihime then confesses to Haruyuki that she loves him and that she will protect him. After Kuroyukihime's confession, she uses a powerful move that only can be used by Burst Linker who is level 9 and above called, Physical Full Burst. It causes her to lose 99% of her burst points and allowing her to manipulate her real body in the Accelerated World to push Haruyuki out of the way of the incoming car, leading to only her being hit.
As Kuroyukihime is taken into intensive care, Haruyuki notices in the live feed that Kuroyukihime is wearing her Neurolinker, and that she is still connected to the global net, leading him to realise that if she was to be attacked by a Burst Linker now, she would be completely vulnerable, and therefore chooses to stay the night. As the morning comes, and the hospital slowly starts to flow with people. Haruyuki spots Takumu coming into the hospital and comes to realize that he is Cyan Pile, as Takumu cannot possibly know about the accident unless he is saw the information through the schools network and therefore meaning he was the one who created the backdoor in Chiyuri's Neurolinker. With just a split second to act, Haruyuki rushes to challenge Takumu to a Brain Burst before he can challenge Kuroyukihime.